Molleton roll for lithographic presses



July 30, l957 c. l.. cLAFF ETAL 2,800,855 MoLLE'roN RoLL FOR LITROGRAPHIC PRESSES Filed Julg 3, 1953.

JNVENTORS CLARENCE LLOYD CLAFF BYCARL A. MOELLER ATTRNEYS United States Patent O 2,800,855 MOLLETON ROLL FOR LITHOGRAPHIC PRESSES Clarence Lloyd Claf and Carl A. Moeller, Randolph, Mass., assignors to M. B. Clatf & Sons, lne., Randolph, Mass., a corporation of Massachusetts Application July 3,1953, Serial No. 366,040

Claims. (Cl. 101--148) In the more usual rotary form of press, these devicesV are' commonly in the form of rolls adapted to bear upon the cylinder supporting the plate. There maybe one or more inking rolls, and one or moremoistening rolls,.these rolls usually being disposed about the plate cylinder in such a way that each portion of the plate passes consecutively" over the moistening roll or rolls, over the inking Vroll or rolls, and over the transfer or blanket cylinder.

Heretofore, it has been commonly believed in the artV that only an extremely limited number of copies couldJ be satisfactorily produced by a press of this type without more or less frequent replenishment of the inkand mois-l tening rolls. Consequently, in the larger presses replenish-l ing means are provided to permit continuous operation, while in the smaller presses it is necessary to stop the printing at intervals to sponge the moistening roll and to replenish the ink by hand, unless other means are provided. l

Where ink and water replenishing means are incorporated into the press to permit continuous opera-tion, they usually take the form of troughs or fountains, and wicks or rolls adapted to transfer the ink or water to the ink or moistening rolls uniformly, and at a rate conforming with that of ink or water depletion. This apparatus increases the cost, weight, diflieulty of maintenance, and

bulk of the press, for which reasons it is usually prefer-l able in the smaller or portable sizes to eliminate the replenishment means altogether in favor of manual replenishment at intervals as required. This greatly reduces the speed of the press, and introduces the further complication of periodically upsetting the balance of the ink and water supplies. Ordinarily, an unreplenished moistening roll tends to dry out more rapidly at its ends, while the center portion remains relatively more moist. Thus, since the depletion of the ink on the surface of the ink roll is relatively more uniform, the longer the press is used without replenishment the more non-uniform the ratio of ink to water supply on the surface of the plate becomes. It is therefore seen that Whenl the press is stopped and the water or inkvreplenished, as by applying a sponge to the moistening roll, the unbalance is further aggravated, since it is extremely unlikely that the ink and water will be replenished in parallel or proportionate i quantities. i

It is therefore a principal object of the present invention to provide a lithographie press of simple construction, having a single moistening roll .and a single inking roll having no external replenishing means, yet capable of printing a much larger number of copies during a con-A tnuous period of operation than has heretofore been possible.: .Another object is to provide an improved `form of mois 2,800,855 Patented July 30, 1957 found to cause erosion and gradual destruction of metallic lithographie plates. Tests made upon lithographie presses of standard construction have shown that a spurious electrolytic action may develop between the plate and the moistening roll, particularly when the moistening roll is wet with acid. Measurements of as much as 0.8 volt, and currents well in 4excess of 45 microamperes have been measured. It is therefore an object of this invention to provide :a form of moistening roll adapted to the ends heretofore mentioned, and further provided with means to minimize this electrolytic action so as to greatly minimize, if not entirely eliminate, the destructive erosion of the plates.

With the above objects in view, a principal feature of the present invention consists in the use of an improved moistening roll having a rigid cylindrical tube surrounded by a porous fabric cover turned into the tube at the ends, and retaining means for the cover including bushings to support the roll upon a shaft, whereby the roll may be replenished, for example, by sponging its external surface, the water passing around the ends of the cover to the inturned extremities, where it is available to replenish the outside surface during operation in much the same manner as a wick.

Another feature is the use of an electrically insulating retaining sleeve adapted to secure the fabric cover firmly upon the tube, and to isolate the tube and cover from the shaft.

According to another feature of the invention, the cylindrieal tube can be imperforate, and the total amount of water which can be supplied to the roll at any one time is limited by saturation of the fabric cover; yet, the rate of moisture diminution during operation of the press closely parallels the rate of diminution of the ink, whereby an exceedingly large number of copies of high quality may be produced before replenishment is again necessary.

Other features and objects of the invention include certain details of construction, modifications, and arrangements which may be more readily understood in relation tothe following description, and which are more particularly defined in the claims.

In the drawings,

Fig. 1 is an end elevation, partially eut away, showing the essential related parts of a lithographie press incorpo-` rating a preferred embodiment of the invention;

Fig. 2 is a longitudinal section of a preferred form of -the moistening roll; and

Fig. 3 is an illustration showing the preferred manner of shaping the in-turned ends of the roll cover.

Fig. 1 shows the principal working components of a roll-fed, or web-fed, rotary olf-set lithographie press. The severing mechanism for the web is assumed to be in position to cut the web into sheets after printing, but

is not shown since it forms no part of the present invention.

The feeding mechanism, including the mechanism for rotating the plate, blanket, and impression cylinders and for feeding the web are of conventional form. The web The feeding force which l I draws the web from the roll 4 is supplied solely and.

continuously by the bite. The blanket roll preferably consists of a metal support with a rubber sleeve 18 vulcanized to its surface, then turned down to shape in accordance with usual practice in forming printing cylinders and the like. In this form of constructionfthere are preferably no discontinuities in the surface, of the sleeve 18. A plate cylinder 20, preferablyl of the same diameter as the blanket cylinder, is mounted upon an axis 24 directly above and in line with the axes of the blanket and impression cylinders. plate 22 is secured to the cylinder 20 by appropriate means, not shown.

The axis 24 of the plate cylinder is movable-vertically being supported in a slidable Yblocki26 movable in a; slot 28 inV the frame 15. Downward force 'is exerted onV the,

block 26 by `aspring 30, and'adjustable screwV means 32, 34 are provided to adjust the pressure of the plate cylinder uponthe blanket.' cylinder.

The inkl roll compisesahard rubber roll4 36 supported 0.11 a. Shaft. 38 isiural'led between, ene: plates 4 0, each.

of the -eind plates having'hooks by which to -hang the roll over a rod 42 secured to the vframe 15. A4 support,

rod 44v joins the end plates 40. to` give rigidity to; the

structure, and to support ahandle bar 46, which is pref-Y erably mounted midway of the roll. The handle 46 isV used'principally foi convenientY removal y ofy thefrollfrom the press andYre-inking by rolling upon a at plate upon which printers ink has; been spread, It also provides manual means for`adjusting the pressure of the ink roll,

upon the plate 22, falthoughfin normal operation, no

pressure need be applied tot-he handle, rsince the shafts 38 an 14`2,are.off-,set from one another, causing the roll 36 to apply a constant, normal component offorce to` the plate.

'The strutureof thenmoisteningroll maybe seen more. readily reference to Fig. 2. This roll has a rigid. cylindrical tube 48, preferably made of stainless steel,

and having a continuousimperforate surface. A porous turned. into the, tube, as shown.

b e noted that, contrary to the usual construction; of molleton rolls, the cover isnot stitched at the ends..

Thej cover is` held inplace by retaining means -comfA prisingretaining sleeves S2 and bushings 54. The'sleeves;V 52 are cylindrical in shape, and preferably constructed',

of Lucite or other electrically insulating material.. The sleeves52v are inserted into eachl end of; thetubeZ 48, preferably meeting in the center when they arefully in position to isolatethe; cover completely from the; shaft to be journalled ,in the bushings 5,4. ThisservesV the dual function of preventing electrical; conduction from.

thecover to the shaft,- and also preventing thetendency of the in-turned ends ofthe cover to wrap. around, thev shaftduring operation of the press. It willibe, obvious that non-insulating,material may be used'forV the sleeves 52 if the bushings 54. are constructed of suitable nonconducting material such as nylon.

Water or other moistening agent is applied to.v the. moistening vroll by wetting the outside surface of` the cover` 50,. for example with a sponge. Whenthis is done, thewater tends to flow around the ends` of the cover to the. extremities thereof on the inside of the tube 48.` The pressure, of the retaining sleeves 52V is notV so great as` to prevent an` appreciable quantity of water. from thus moistening the inner periphery of the cover. When the printing operation is begun, the moisture on the surface of the cover 50 tends tobe depleted' more rapidlyl atgthe ends' than elsewhere, as heretofore described. However, by reason of the'moisture'in-the in-turned` ends of the cover, a capillary flowsimilar to the-:action of a-wick takesl'place.

The moisture flows copies.

out around the ends the tube 48 and replenishes the surface of the roll, starting at the ends where depletion is more rapid, and working toward the center portion.

The results observable with this construction are somewhat surprising. It is expectable that the moistening roll should produce more acceptable copies without replenishing than a roll having no in-turned ends, simply by reason of the increased Water capacity. However, the increase in the number of acceptable copies which may be turned out consecutively without replenishment is substantially out of proportion to what might be expected from the increased capacity alone. For example, a press constructed in accordance with this invention has actually produced as many as 1500 highly legible copies from a paper plate without al single replenishment or stoppage of the press for any reason.

In part, these results are attributable to the fact that the replenishing process takesl place smoothly and evenly from the ends of the roll. In large measure, however, they results are due to the fact that with this novel construction it is possible to so design the press that'the rates o f ink -and-water depletionr` remain parallel for a considerably longer time than is possible with presses not incorporating automatic and continuous replenishing means. Itis apparently this balance of rates of depletion, rather than the absolute quantities of available ink and moisture, which principally determinesy the legibility of Thus, by using 'the constructiton herein described, it has now become possibleV to adjust the above balance to receive the great benefits which may be de- .'rived therefrom. For example, the balance may be effected by using a choiceV of covering materials, or by changing the relative diametersof theink and moistening rolls. Different kinds of ink may also affect the. balance.

b alance, and thisis more readily achieved withv the particular construction` of moistening rolls herein described.

It will be vunderstood that many variations of construction, arrangements of parts, and variationsof design may be made in the apparatusin accordance with procedures and techniques well known in the art, and without depart'- departing from the spirit and. scope of the invention.

Having thus described'our invention, we claim:

1. A moistening roll for aY lithographie press, comprising a rigid imperforate cylindrical tube, a porous teriorof the tube, the cover intermediate the sleeves andv the Itube being free to transfer moisture between the cover outwardly of theroll and the inturnedl ends-inwardly of the tube.

2. A moistening roll for a lithographie press, comprising a rigid-imperforatecylindrical; tube, a porous Yfabric cover surroundingthetube, said cover beingfadapted' to permit capillary flow of liquid therethroughand beingsubstantially longer than the ,tube and havingits ends turned inwardly of' theends oft the tubefandlextending into-the' interior thereof, sleeves within the inturned cover portions adjacent therouter ends of the interior of the Vtubethe cover intermediate-the sleeves and thetube being free to` transfer moisturel between'- the cover outwardly of the roll and the inturned 'ends inwardlyof the tube, and means including said sleeves for supportingthe rolliuponY a-shaft, the sleeves being of insulating material to electrically insulate thel tube: from the shaft.

3.- A moisteningvroll for a1 lithographie press, comprisinga rigid imperforate cylindrical tube,- a porous fabriccover surrounding thetube, said cover being-adapted .to permit capillaryfflow` of liquid therethrough andzbeing substantially longer than the tube and having itsV ends turned inwardly of the Aendsof-.the tube and extending into the interior thereof, sleeves within the inturned cover portions adjacent the outer ends of the interior of the tube, the cover intermediate the sleeves and the tube being free to transfer moisture between the cover outwardly of the roll and the inturned ends inwardly of the tube, means including said sleeves for supporting the roll upon a shaft, the sleeves being of insulating material to electrically insulate the tube from the shaft, and means for preventing electrical contact of the inturned ends of the cover with the shaft.

4. A moistening roll for a lithographic press, comprising a rigid imperforate cylindrical tube, a porous fabric cover surrounding the tube, said cover being adapted to permit capillary 110W of liquid therethrough and being substantially longer than the tube and having its ends turned inwardly of the ends of the tube and extending into the interior thereof, sleeves within the inturned cover portions adjacent the outer ends of the interior of the tube, the cover intermediate the sleeves and the tube being free to transfer moisture between the cover outwardly of the roll and the inturned ends inwardly of the tube, and means including said sleeves for supporting the roll upon a shaft, the sleeves being of insulating material to electrically insulate the tube from the shaft, said sleeves having portions extending inwardly of the tube to maintain the inturned ends of the cover material out of electrical contact with the shaft.

5. A lithographic press having ink-supplying means consisting of a single ink roll adapted to carry on the surface thereof a supply of ink suicient to permit printing for a substantial period without replenishment and moisture-supplying means consisting of a single moistening roll adapted to carry a self-contained supply of liquid for operation for a period substantially coextensive with the period of ink supply, the moistening roll comprising an imperforate tube, a porous fabric cover surrounding the tube and having extended end portions turned into and extending a substantial distance inwardly within the tube, roll supporting means within the tube ends inside the inturned cover material, said roll supporting means securing the inturned cover material adjacent the tube ends While permitting moisture transfer to the cover material within the tube when the cover outwardly of the tube is moistened, whereby said moistened inturned ends provide a source of moisture supplementing the moistened outside cover to afford a substantially constant ink/moisture ratio as the ink and moisture are consumed during press operation.

References Cited in the file of this patent UNITED STATES PATENTS 452,049 Spitzer May 18, 1886 352,351 Pope Nov. 9, 1886 689,590 Johnson Dec. 24, 1901 934,076 Kneuper Sept. 14, 1909 1,180,569 Chisholm Apr. 25, 1916 2,483,203 Janke Sept. 27, 1949 2,588,470 Bassist Mar. 11, 1952 2,591,530 Findley Apr. 1, 1952 2,684,497 Graham July 27, 1954 

